A water-containing specimen is normally observed using a scanning electron microscope (SEM) in a state in which the water-containing specimen has been frozen. In this case, however, the original state of the specimen may not be observed since the water contained in the specimen is not present in the form of a liquid.
In order to observe the original state of a water-containing specimen, it is necessary to keep the water contained in the specimen in a liquid phase. In order to keep the water contained in the specimen in a liquid phase when observing the specimen using a low-vacuum-mode scanning electron microscope, it is necessary to maintain the pressure inside the specimen chamber at about 650 Pa, and maintain the temperature of the specimen at 0° C. to 1° C.
However, when a water-containing specimen that is observed using a scanning electron microscope is loaded directly into the specimen chamber, evaporation of water may occur (i.e., the specimen may dry) during an evacuation step that is performed to achieve the observation conditions. Moreover, the temperature of the specimen may decrease due to heat of evaporation that is generated when the water evaporates from the specimen, whereby the specimen may freeze.
For example, Patent Literature 1 discloses a scanning electron microscope that includes a microinjection device that supplies a trace amount of liquid through a thin tube that is provided from the wall of the specimen chamber to the specimen stage. It is possible to prevent a situation in which the specimen dries by utilizing the scanning electron microscope disclosed in Patent Literature 1. However, since it is necessary to provide the thin tube that connects the inside and the outside of the specimen chamber, the device configuration necessarily becomes complex.